Electromagnetic relay

ABSTRACT

An improved electromagnetic relay including a movable contactor arm made of a conductive rigid plate material. The arm is bent upward adjacent the opposite end to the movable contactor end thereof and supported rockably on a bottom face having a tapered section at the contactor side of an insulative arm-supporting frame secured on the armature for integral actuation therewith. The frame includes a spring for biasing the arm downward at a position between the tapered corner of frame bottom and the bent corner of the arm, so that, in non-excited state of electromagnet, the movable contactor is urged against a normally closed contact by the downward biasing applied with the tapered corner as fulcrum and, in excited state, the contactor is urged reversely against a normally opened contact by the same biasing applied with the bent corner as fulcrum. The frame may include forcibly opening means for contacts adjacent both the tapered and bent corners.

United States Patent Nagamoto et al.

ELECTROMAGNETIC RELAY Inventors: Mitsuki Nagamoto; Yutaka Sato,

both of Tsu-shi, Japan Assignee: Matsushita Electric Works, Ltd.,

Osaka, Japan Filed: April 22, 1971 Appl. No.: 136,508

Foreign Application Priority Data April 22, 1970 Japan ..45/34598 May13, 1970 Japan ..45/46561 May 26, 1970 Japan ..45/52110 US. Cl..335/200, 335/187 Int. Cl. ..Hlllh l/l2 Field of Search ..335/202, 203,135, 128, 187,

335/196, 200; 200/166 J, 67 PK References Cited UNITED STATES PATENTSAug. 15, 1972 2,870,282 1/1959 Brand 200/67 PK Primary Examiner-HaroldBroome AttorneyWolfe, Hubbard, Leydig, Voit & Osann 5 7] ABSTRACT Animproved electromagnetic relay including a movable contactor arm made ofa conductive rigid plate material. The arm is bent upward adjacent theopposite end to the movable contactor end thereof and supported rockablyon a bottom face having a tapered section at the contactor side of aninsulative arm-supporting frame secured on the armature for integralactuation therewith. The frame includes a spring for biasing the armdownward at a position between the tapered corner of frame bottom andthe bent corner of the am, so that, in non-excited state ofelectromagnet, the movable contactor is urged against a normally closedcontact by the downward biasing applied with the tapered comer asfulcrum and, in excited state, the contactor is urged reversely againsta normally opened contact by the same biasing applied with the bentcorner as fulcrum. The frame may include forcibly opening means forcontacts adjacent both the tapered and bent comers.

6 Claims, 6 Drawing Figures PAIENTEDAus 1 5 m2 SHEU 2 0F 3 mvswons MlTau/(1 nomoro BY VUTAKA Snro ATTORNEYS W05 5AM 04 ELECTROMAGNETIC RELAYThis invention relates to an electromagnetic relay.

Conventional electromagnetic relays of this kind have been of suchstructure that the movable contact provided on the contact arm ofelastic conductive material has been provided between fixed contacts.Since such movable contact arm has been made of an elastic material, theuse of thick material might reduce elasticity of the material and,therefore, it has been impossible to increase current capacity of themovable contact arm.

Further, in the case when there occurs a fusing trouble between themovable contact and either one of the fixed contacts and thereby theboth contact points are fused together, it is necessary to forcibly opensuch fused contact points by a proper means. However, since in theconventional relays the movable contact arm is elastic and, thus, even aforcibly opening mechanical means is provided for such fused contactsthe intended opening operation of the means is caused to be not reliableor even not effective due to the elasticity of the contact arm whichwill absorb the force of such means.

The present invention is proposed to obviate the above mentioneddrawbacks and solves the problems in that a rigid conductive member isused as the movable contact arm and the member is biased by a spring toapply proper contact pressure thereto against the fixed contact.

It is, therefore, a principal object of the present invention to providean electromagnetic relay of small size and yet of a high capacity.

Another object of this invention is to provide an electromagnetic relaywhich is easy to assemble on account of simple structure adapted tosupport the movable contact arm.

It is a further object of the present invention to provide anelectromagnetic relay which performs stable and reliable relayingoperation even when movable and fixed contacts are fused together, whichfused contacts will be positively opened with a forcible opening meansfor such fused contacts provided in addition to the above describedcombination of the rigid contact arm and the biasing spring.

Other objects and advantages will be made clear as the followingdetailed disclosures advance with reference to the accompanyingdrawings, in which:

FIG. 1 is a perspective view of an embodiment of the electromagneticrelay according to the present invention;

' FIGS. 2A and 2B are sectional views of the electromagnetic relay inFIG. 1, and FIG. 2A shows nonexcited state of the electromagnet and FIG.2B shows excited state of the same;

FIG. 3 is an exploded perspective view of the movable contact mechanismin the relay shown in FIG. 1; and

FIGS. 4A and 4B shown in fragmental sections another embodiment in whicha fused contact forcibly opening means is provided, FIG. 4A showing anoperating state of said means in which normally closed fixed contact andmovable contact are fused together and do not open even theelectromagnet is excited, and FIG. 48 showing another operating state ofthe means in which normally opened fixed contact and the movable contactare fused together and do not return to the normally open state even theexcitation of the electromagnet is interrupted.

The present invention will now be disclosed with reference to preferredembodiments as illustrated, but it is not the intention to limit theinvention to such particular embodiments. It should be appreciated thatthe intention is rather to include all alterations, modifications andequivalents within the scope of appended claims.

In the drawings, 1 designates a base plate made of insulating material,on one side of which are integrally provided a normally closed terminal2, a normally opened terminal 3, a common terminal 4 and coil terminals5, and said terminals 2 and 3 extend through the base plate 1 to formnormally closed fixed contact 6 and normally opened fixed contact 7 onthe opposite side of the base plate 1. In the drawing, four pairs offixed contacts are shown (FIG. 1). 8 is a partition provided betweenadjacent pairs of the contacts. 9 is a movable contact arm and 10 is amovable contact provided thereon.

11 indicates an electromagnet, whose yoke 12 formed substantially in aU-shape in section is secured to the base plate 1 at its one of itsupright legs. 13 is an armature provided with a notch 14 at each cornerof one side thereof, and a projection 15 provided at end portion of theother upright leg of the U-shaped yoke 12 engages in said notch 14 torotatably support the armature 13 above the yoke. 16 is a projectionformed at said side of the armature 13 adjacent each of the notches 14,at which an end of a tension spring 17 engages. The other end of thespring 17 is engaged in a hole 18 provided in the yoke 12.

19 is a lower frame made of an insulating material and secured at itsbottom face to the upper face of the armature 13. 20 is an upper framemating with the lower frame 19. Said lower and upper frames 19 and 20constitute a holding frame 39 as assembled together. The base portion ofthe movable contact arm 9 is inserted into and held between the upperframe 20 and the lower frame 19.

Next, the structure of the upper and the lower frames will be describedin more details.

In FIG. 3, showing a movable contact assembly including two contactarms, the upper frame 20 is formed substantially in reverse U shape insection so as to be provided with a U-shaped groove 21. The frame 20 isfurther provided at the central portion of respective lateral downwardwall portions with downwardly extending legs 22. Inside the tip of eachleg 22, there is provided inward projection 23. Walls 24, 25 and 26 areformed in parallel to each other on the both sides and central portionof the lower frame 19 and an upward projection is formed on each of saidwalls to allow them to engage in the U-shaped groove of the upper frame20. A pair of engaging holes 27 are provided at both side ends of thecentral wall 25 for receiving therein the legs 22 and inward projections23 of the upper frame 20, and vertical grooves 28, 29, 30 and 31 areformed respectively at each inside surface of the respective walls 24,25 and 26. 32 is a straight bottom section provided on the bottomsurface in each channel between said walls of the lower frame 19, and atapered portion is formed on one side of the bottom portion 32 so as tobe inclined toward the contacts.

9 is a movable contact arm made of conductive rigid material, which isprovided at one end with the movable contact 10 and is bent at the otherend so as to form a bent arm 34. Two movable contact arms 9 are mountedin the movable contact assembly shown, respectively between the walls 24and 25 and between the walls 25 and 26 on the lower frame 19 engagingrespective projections 35 formed on both lateral sides of the arm 9 inthe vertical grooves 28, 29, 30 and 31 provided on the lower frame 19.One end'of a compression coil spring 36 rests on the contact arm 9 andthe upward projections of the walls 24, 25 and 26 of the lower frame 19are fitted in the groove 21 of the upper frame 20 resting on the otherend of the coil spring 36. The legs 22 and inward projections 23 of theupper frame 20 are engaged in the respective engaging holes 27 of thelower frame 19, whereby the upper frame 20 is fixed to the lower frame19 to provide a supporting frame 39 for the movable contacts. 37 arelead wires for the movable contact arms 9.

In the embodiment shown in FIGS. 4A and 4B, the supporting frame 39 isprovided in the respective channels of the lower frame 19 with lateralprojections 40 and 41 projecting above the contact arms 9 from thewalls, which act as a means for forcibly opening the movable and fixedcontact specifically effective at the time when the contacts areaccidentally fused together due to discharge sparks occuring betweenthem. The projection 40 is positioned at the side of contact points withrespect to the biasing point of the spring 36 and the other projection41 is positioned at the other side of the spring 36 so as to be adjacentthe bent part 34 of the movable contact arm 9.

Operation of the electromagnetic relay according to the presentinvention will be explained in the followings.

FIG. 2A shows the electromagnet 11 under nonexcited condition and, inthis condition, the movable contact arms 9 are supported in their upwardposition by the boundary edge line, as a fulcrum a, between the bottom32 and the tapered section 33 of the lower frame 19. Since the movablecontact arm 9 is urged downward by the compression of the spring 36 atthe right side of the arm in the drawing with respect to the fulcrum a,the side of the contact 10 of the contact arm 9 is urged upward and,thus, the contact 10 is brought into close contact with the normallyclosed contact 6.

FIG. 2B shows the state in which the electromagnet 11 is under excitedcondition. The armature 13 is attracted by the core 38 and the contact10 in contact with the contact 6 is separated from the contact 6. Inthis state, the movable contact arm 9 is supported by the bent edge lineas a fulcrum b of the bent arm 34 of the arm 9 and, since the left sideof the movable contact plate 9 is urged downward by the compression ofthe spring 36, the contact 10 on the same side as the spring 36 on thearm 9 with respect to the fulcrum b turnes into contact with thenormally opened contact 7.

Next, the operation of forcible opening of the contacts in the secondembodiment having the forcible opening means for fused contacts withreference to FIGS. 4A and 4B.

As described in the foregoing, when the electromagnet 11 is undernonexcited condition, the movable contact 10 of the arm 9 is in contactwith the normally closed contact 6 as raised with the point a as thefulcrum in consequent to downward biasing force of the spring 36, as inFIG. 2A. If these contacts 6 and 10 are fused together due to skarkingtrouble therebetween, the both contact points will not open due to thefusing, even when the electromagnet 11 is excited and the armature 13 aswell as the frame 39 is attracted downwardly as shown in FIG. 4A so thatthe contactor side of movable contact arm 9 is subjected to downwardurge of the spring 36 with the point h as the fulcrum. During thedownward movement of the armature and the frame, however, the projection40 pro vided on the lower frame 19 so as to be above the contact arm 9will simultaneously be lowered and will abut against the arm 9 so as topush the latter downward, thereby the fused contacts will be forciblyseparated to open. Depending on subsequent downward movement of thearmature and frame due to the electromagnetic attraction, the thusseparated movable contact arm 9 will then be brought into contact withthe normally opened contact 7 due to the biasing force of the spring 36with the point I) as the fulcrum and, thus, the relay will reach thenormal excited state as shown in FIG. 28. At the time when, on the otherhand, the normally opened fixed contact 7 and thc movable contact 10 arefused together, these contacts will not open even if the electromagnet11 returns to non-excited state and the armature and the frame arelifted upward due to the tension of the return spring 17. At the nextmoment, however, the other projection 41 of the frame 19 will abutagainst the contact arm 9 at the side of the bent section 34 which islifted at this time with the point a as the fulcrum so as to push saidside downward, thereby the contacts 7 and 10 fused together will beforcibly separated from each other. Depending on subsequent upwardmovement of the armature and frame as pulled up by the spring 17, thethus opened contact arm 9 will be lifted up with the point a as thefulcrum until it reaches the normally closed fixed contact 6, wherebythe relay will be returned to the normal non-excited state of FIG. 2A.

While in the above embodiment the projections 40 and 41 are disclosedand illustrated in such form that they extend inwardly from the bothopposing walls 24, 25 and 25, 26 and horizontally above the contact arm9, it will be readily appreciated that in lieu of the above form a pairof projections provided, for example, at lower edges of the respectivedownward walls of the reverse U-shaped upper frame 20 so as to extenddownwardly into the channel in which the contact arm is placed, willperform exactly the same effect.

The present invention is featured in that since the movable contact arm9 made of conductive rigid material is disposed in the space between theupper frame 20 and the lower frame 19 having the bottom 32 provided withthe straight section and the tapered section 33, said contact arm 9having the movable contact 10 at one end thereof and the bent portion 34at the other end thereof, and the compression spring 36 urges themovable contact arm 9 downward so as to urge the contact 10 of themovable contact arm 9 into the contact with either one of the fixedcontacts, the specific resistance of the contact arm 9 is effectivelyreduced due to the use of the rigid conductive material which isrelatively large in section, as compared with conventional resilientcontact arm. This results in that any heat apt to be generated at thearm is reduced and, there fore, comparatively large electric current canbe utilized. This means that an electromagnetic relay of a highercapacity can be obtained. Since the contact pressure is determined bythe force of the compression spring utilized in combination with therigid contact arm, the spring constant of this spring can be freelydetermined and assembly work of the relay is easy.

Another feature resides in that, since the movable contact arm 9 made ofrigid conductive material is disposed with the associated coil spring 36between the upper frame and the lower frame 19 devided into two piecesso as to form the movable contact holding frame 39 it is easy toincorporate the movable contact arm into the frame and also it ispossible to simplify the structure of the movable contact arm mechanismof the electromagnet relay.

Further according to the present invention, the relay can perform itsrelaying operation stably and reliably even when such trouble that thecontacts are fused together due to sparkings therebetween is caused tooccur, since the holding frame 39 is provided with the projections 40and 41 which extend above and in proximity to the movable contact arm 9respectively at the side of the contact point and the opposite sidethereto with respect to the compression spring 36, so that, even whenthe movable contact is fused to the normally closed contact point or thenormally opened contact, the projection 40 at the contact point side ofthe arm will push down the arm in the instance of the armatureattraction due to the excitation of the electromagnet, or the oppositeside projection 41 will push down the arm in the event of the armaturereturn due to non-excitation, and thereby the fused-together contactsare forcibly separated and opened from each other.

What is claimed is:

1. An electromagnetic relay comprising the combination of an insulatingbase, at least one pair of spaced apart fixed contacts mounted on saidbase, a movable contact member cooperating with said fixed contacts, anarmature pivotally mounted for moving said movable contact member backand forth between said fixed contacts, an electromagnetic device forpivoting said armature to move said movable contact member, aninsulating holding member carried on said armature for pivoting movementtherewith and forming an opening for receiving a portion of said movablecontact member, a single compression spring inserted in said holdingmember for urging said portion of said movable contact member against anopposed surface of said holding member, said opposed surface of saidholding member having a first area which forms a first fulcrum for saidmovable contact member on one side of said spring when said armature isnot attracted by said electromagnetic device so that said spring urgessaid movable contact member toward a first one of said fixed contacts,and a second area which forms a second fulcrum for said movable contactmember on the opposite side of said spring when said armature is attracted by said electromagnetic device so that said spring urges saidmovable contact member toward a second one of said fixed contacts, saidspring being located about centrally between said first and secondfulcrums.

2. The electromagnetic relay according to claim 1 which includes springmeans for urging said armature away from said electromagnetic device soas to urge said movable contact member toward said first fixed contactwhen said armature is not attracted by said electromagnetic device.

3. The electromagnetic relay according to claim 1 wherein said movablecontact member comprises a plate of rigid and conductive material.

4. The electromagnetic relay according to claim 1 wherein said holdingmember comprises an upper frame substantially in a U shape in sectionand a lower frame engaged with said upper frame, said lower frame havingupright walls provided with vertical grooves receiving therein lateralprojections provided at both sides of the movable contact member.

5. The electromagnetic relay according to claim 3 wherein said holdingmember comprises an upper frame substantially in a U-shape and a lowerframe engaged with said upper frame, said lower frame having uprightwalls provided with vertical grooves receiving therein lateralprojections provided at both sides of the movable contact member.

6. The electromagnetic relay according to claim 1 wherein said holdingmember is provided with a pair of projections for forcibly openingfused-together contacts said projections being positioned on oppositesides of said compression spring and in alignment with the movablecontact member so that the movement of said holding member brings one ofsaid projections into engagement with said contact member in the eventof a fusing together of a pair of said contacts.

1. An electromagnetic relay comprising the combination of an insulatingbase, at least one pair of spaced apart fixed contacts mounted on saidbase, a movable contact member cooperating with said fixed contacts, anarmature pivotally mounted for moving said movable contact member backand forth between said fixed contacts, an electromagnetic device forpivoting said armature to move said movable contact member, aninsulating holding member carried on said armature for pivoting movementtherewith and forming an opening for receiving a portion of said movablecontact member, a single compression spring inserted in said holdingmember for urging said portion of said movable contact member against anopposed surface of said holding member, said opposed surface of saidholding member having a first area which forms a first fulcrum for saidmovable contact member on one side of said spring when said armature isnot attracted by said electromagnetic device so that said spring urgessaid movable contact member toward a first one of said fixed contacts,and a second area which forms a second fulcrum for said movable contactmember on the opposite side of said spring when said armature isattracted by said electromagnetic device so that said spring urges saidmovable contact member toward a second one of said fixed contacts, saidspring being located about centrally between said first and secondfulcrums.
 2. The electromagnetic relay according to claim 1 whichincludes spring means for urging said armature away from saidelectromagnetic device so as to urge said movable contact member towardsaid first fixed contact when said armature is not attracted by saidelectromagnetic device.
 3. The electromagnetic relay according to claim1 wherein said movable contact member comprises a plate of rigid andconductive material.
 4. The electromagnetic relay according to claim 1wherein said holding member comprises an upper frame substantially in aU shape in section and a lower frame engaged with said upper frame, saidlower frame having upright walls provided with vertical groovesreceiving therein lateral projections provided at both sides of themovable contact member.
 5. The electromagnetic relay according to claim3 wherein said holding member comprises an upper frame substantially ina U-shape and a lower frame engaged with said upper frame, said lowerframe having upright walls provided with vertical grooves receivingtherein lateral projections provided at both sides of the movablecontact member.
 6. The electromagnetic relay according to claim 1wherein said holding member is provided with a pair of projections forforcibly opening fused-together contacts said projections beingpositioned on opposite sides of said compression spring and in alignmentwith the movable contact member so that the movement of said holdingmember brings one of said projections into engagement with said contactmember in the event of a fusing together of a pair of said contacts.